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One-step preparation of nanoparticles-assembled hollow Fe 3 O 4 /C microsphere composites was achieved by an energy-efficient and continuous ultrasonic spray pyrolysis process. Systemically characterizations by scanning and transmission electron microscopy, X-ray diffraction, and Raman spectroscopy suggest that the physical and structure properties are highly dependent on the pyrolytic temperature; the outer surface of the hollow Fe 3 O 4 /C products are actually built by mesoporous carbon nanosheets overlaying Fe 3 O 4 nanoparticles. Attributing to the synergistic effect of connected carbon layers and moderate hollow microsphere configuration with mesoporous nature, the optimal Fe 3 O 4 /C composites obtained at 800 °C deliver an initial specific discharge and charge capacity of 1236.0 and 1034.0 mAh g −1 with an initial coulombic efficiency of 83.65% at 0.1 A g −1 , and the specific capacity can recover to above 1030 mAh g −1 after suffering 100 cycles when the current density was reduced from 4 to 0.1 A g −1 . The present report may open up a promising opportunity to push forward application for next generation Li-ion batteries. [ABSTRACT FROM AUTHOR]

• The concept of fluorine doped carbon is proposed; • Polyvinylidene fluoride is used as carbon and fluoride source; • The optimal LFP@F-doped carbon nanocomposites delivered a practical capacity and cyclability. The present work presents an insightful study on the effect of fluorine doped carbon (FC) modification on the electrochemical performance of LiFePO 4 cathode material. To this end, polyvinylidene fluoride is used as fluoride source to synthesize FC, which is designed to coat on LiFePO 4 surface with formation of LiFePO 4 @FC nanocomposites. The microstructure and electrochemical properties of the nanocomposites are systematically examined by various characterization techniques, revealing that FC is tightly attached on surface of LiFePO 4 particles forming a three dimensional (3D) conductive network structure. Such favorable structure provides advantages of good grain-to-grain electrical contact, shortening the Li+ diffusion distance between the grain interfaces, and facilitating the rapid transfer of electrons during charge–discharge. The optimal LiFePO 4 @FC nanocomposites, i.e. , with 97.2 wt% of LiFePO 4 , are verified to show highly desirable electrochemical performance with superior rate capability and excellent cycling performance as the cathode material of lithium-ion batteries. [ABSTRACT FROM AUTHOR]